Brookhaven Neutrino Research

Tens of billions of neutrinos are passing through every square centimeter of the Earth’s surface right now.

A Ghost-Particle Retrospective

Neutrinos, ghostlike particles that flooded the universe just moments
after the Big Bang, are born in the hearts of stars and other nuclear
reactions. Untouched by electromagnetism and nearly as fast as light,
neutrinos pass practically unhindered through everything from planets
to people, only rarely responding to the weak nuclear force and the even
weaker gravity. In fact, at any given moment, tens of billions of neutrinos
are passing through every square centimeter of the Earth’s surface,
undetected. This ability to sail unhindered and unnoticed through almost
anything earned neutrinos the nickname “ghost” particles. But despite their
imperceptibility, neutrinos could be the key to understanding how our
universe evolved just after the Big Bang and why the world is made of
matter.

Neutrino Research News

The Goldhaber Helicity Experiment

Brookhaven Lab’s first major contribution to neutrino research
occurred in 1957, when Maurice Goldhaber performed an experiment that
revealed neutrinos to be "left-handed." That is, a property of neutrinos
known as "spin" is always oriented counter-clockwise to the direction of
their linear momentum.

Discovery of the Muon Neutrino

In 1962, a new type of neutrino, the muon neutrino, was discovered by
scientists using the Alternating Gradient Synchrotron at Brookhaven. Leon
Lederman, Mel Schwartz, and Jack Steinberger took home the 1988 Nobel Prize
for this work, which established that there was more than one flavor of
neutrino.

The Solar Neutrino Problem

In the late 1960s, Brookhaven chemist Ray Davis discovered the solar
neutrino problem. At the Homestake Mine in South Dakota, deep
underground in order to shield the detector from cosmic rays, Davis was
the first person able to directly detect the electron neutrinos being
produced by the sun. But he only observed about one-third of the
expected amount — this deficit would eventually become known as the
solar neutrino problem (and the “missing” neutrinos would later turn out
to be those that had changed to forms undetectable by Davis’ experiment
while en route to Earth).

Brookhaven’s Maurice Goldhaber was also a founding member of a
pioneering experiment built in the Morton salt mine in Ohio in the
early 1980s that became famous for observing neutrinos from Supernova
1987A (along with the Kamioka detector in Japan). Originally designed
to study proton decays, the experiment was a six-story cube lined with
black plastic and a network of phototubes and filled with 2.5 million
gallons of ultra-pure water. The neutrinos showed up by way of their
interactions with protons in the water.

GALLEX and SNO

From the 1990s through the mid-2000s, Brookhaven's
neutrino group played important roles in the GALLEX (Gallium
Experiment) and SNO (Sudbury Neutrino Observatory)
experiments in Italy and Canada, respectively. Brookhaven chemist Richard Hahn and his group were integral to
the SNO experiment, which proved that neutrinos do oscillate between
three forms — electron, muon, and tau.

Super-Kamiokande

Meanwhile, the Super-Kamiokande experiment in Japan, in
which Brookhaven was
represented by physicist and former Lab Director Maurice Goldhaber, had
confirmed that neutrinos do indeed oscillate and have mass. Davis’s
problem was solved: he had observed only the fraction of electron
neutrinos from the sun that reached Earth without changing into muon or
tau neutrinos. In 2002, his work was acknowledged with the Nobel Prize
in Physics, shared with Masatoshi Koshiba of Japan and Riccardo Giacconi
of the U.S.

MINOS

Brookhaven then became involved in the ongoing MINOS (Main Injector Neutrino
Oscillation Search) experiment based at Fermi National Accelerator
Laboratory in Illinois, which began taking data in 2005 and has since
provided measurements of mixing angles and oscillation frequency that
describe how muon and tau neutrino types oscillate between one form and
another.

Daya Bay

In addition, Brookhaven is integral to the Daya
Bay Neutrino Project, which began taking data in 2011. This
experiment aims to measure the final unknown mixing angle that describes
how neutrinos oscillate — another chapter in Brookhaven’s long history of
neutrino research over the last several decades.

MicroBooNE Cryogenic Neutrino Detector

Many Brookhaven scientists played leading roles in the design and
construction of the MicroBooNE cryogenic neutrino detector, located at
Fermilab. MicroBooNE represents the latest development of massive liquid
argon Time-Projection-Chamber detectors for neutrino physics—a particle
physics detector design pioneered by physicists in Brookhaven Lab’s
Instrumentation Division. Brookhaven physicists also built MicroBooNE’s
custom electronics, designed to operate at cryogenic temperatures. The
experiment is expected to start collecting data in mid-2015.

Long Baseline Neutrino Experiment (LBNE)

In the early 2000s, Brookhaven Lab scientists conceived an experiment
to produce an intense collimated beam of neutrinos that would travel
hundreds of miles through the Earth and strike a distant target to help
unravel the mysteries of matter. Traveling over such a long distance
would give the particles time to exhibit one of their strangest and most
exciting quirks: quantum mechanical flavor transformations. Understanding
details of these oscillations is one of the most important puzzles in
fundamental physics. The project was eventually approved as the
Long-Baseline Neutrino Experiment
(LBNE), with the beam initiating at Fermi National Accelerator Laboratory
(Fermilab) and striking a very large precision, underground detector
capable of identifying and measuring neutrino events at the Sanford
Underground Research Facility in Lead, South Dakota. Brookhaven Lab
scientists were principal collaborators in this experiment, from
fundamental neutrino science to beam and detector design, prototyping
and construction. This program has now evolved into a large international
enterprise known as the Long-Baseline Neutrino Facility (LBNF) and the
Deep Underground Neutrino
Experiment (DUNE).

Deep Underground Neutrino Experiment

The Deep Underground Neutrino Experiment (DUNE)
is a growing international collaboration with currently more than 750
scientists. This collaboration will build and operate a huge liquid argon
Time-Projection-Chamber detector in the Sanford Underground Research
Facility (SURF) in Lead, SD, as well as a smaller detector on the Fermilab
site. This experiment will build on Fermilab’s existing accelerator complex
to supply its neutrinos. Fermilab’s Main Injector Ring will produce an
intense collimated beam of neutrinos that will travel 800 miles through
the Earth before striking its target at SURF (based in the same Homestake
Mine in which Ray Davis did his famous experiment). Brookhaven Lab is one
of the principal collaborators in the planning, design, and operation of
this experiment. From fundamental neutrino science to beam and detector
design, prototyping and construction, Brookhaven Lab has had a foundational
role in DUNE.

Former Brookhaven Director Maurice Goldhaber

1988 Nobel Prize winner Mel Schwartz

2002 Nobel Prize winner Ray Davis Jr.

GALLEX and SNO collaborator Richard Hahn

One of ten national laboratories overseen and primarily funded by the Office of Science of the
U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical,
biomedical, and environmental sciences, as well as in energy technologies and national security.
Brookhaven Lab also builds and operates major scientific facilities available to university, industry
and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven
Science Associates, a limited-liability company founded by the Research Foundation for the State
University of New York on behalf of Stony Brook University, the largest academic user of Laboratory
facilities, and Battelle, a nonprofit applied science and technology organization.